Antireflective (AR) coatings are known in the art. For example, AR coatings in the visible range are widely used on glass in electronics, lighting, appliances, architectural, and display applications. However, in many of these applications, tempered or heat-strengthened glass may be required. Tempering or heat strengthening of the glass is sometimes done prior to the deposition of the AR coating to avoid unwanted changes in the optical, mechanical, or aesthetic quality of the coating as a consequence of exposing the coating to the high temperatures required for tempering and other forms of heat treatment. However, this “temper then coat” method may be undesirable in certain circumstances. Thus, it will be appreciated that there exists a need in the art for improved antireflective (AR) coatings (e.g., temperable AR coatings) for coated articles such as windows and the like.
In certain example embodiments, there is provided a coated article comprising an antireflective coating supported by a major surface of a substrate, the substrate being heat treated together with the antireflective coating, wherein the antireflective coating comprises, in order moving away from the substrate: a medium index layer comprising silicon oxynitride and having a index of refraction of from about 1.65 to 2.0 at 380 nm, 550 nm, and 780 nm wavelengths, a high index layer having an index of refraction of at least about 2.0 at 380 nm, 550 nm, and 780 nm wavelengths, and a low index layer having an index of refraction of from about 1.4 to 1.6 at 380 nm, 550 nm, and 780 nm wavelengths, wherein the medium index layer has compressive residual stress after heat treatment.
In certain example embodiments, there is provided a heat treatable coated article, the coated article comprising: an antireflective coating supported by a major surface of a substrate, wherein the antireflective coating comprises, in order moving away from the substrate: a medium index layer comprising silicon oxynitride and having a index of refraction of from about 1.65 to 2.0 at 380 nm, 550 nm, and 780 nm wavelengths, a high index layer having an index of refraction higher than that of the medium index layer at 380 nm, 550 nm, and 780 nm wavelengths, and a low index layer having an index of refraction lower than that of the medium index layer at 380 nm, 550 nm, and 780 nm wavelengths, wherein the medium index layer and the low index layer have compressive residual stress after any heat treatment, the high index layer has tensile residual stress after any heat treatment, and the antireflective coating has a net compressive residual stress.
In certain example embodiments, there is provided a heat treatable coated article, the coated article comprising an antireflective coating supported by a major surface of a substrate, wherein the antireflective coating comprises, in order moving away from the substrate: a medium index silicon-inclusive layer having a index of refraction of 1.8 or less 550 nm and 780 nm wavelengths and 2.0 or less at 380 nm, a high index layer having an index of refraction higher than that of the medium index layer at 380 nm, 550 nm, and 780 nm wavelengths, wherein the high index layer has a thickness no greater than about 20 nm, and a low index layer having an index of refraction lower than that of the medium index layer at 380 nm, 550 nm, and 780 nm wavelengths, wherein the medium index layer and the low index layer have compressive residual stress, the high index layer has tensile residual stress, and the antireflective coating has a net compressive residual stress.
In certain example embodiments, there is provided a method of making a coated article with a three-layered antireflection coating, the method comprising: disposing a medium index layer, directly or indirectly, on a glass substrate; disposing a high index layer over and contacting the medium index layer; disposing a low index layer over and contacting the high index layer; and heat-treating the glass substrate with the antireflective coating thereon, and wherein the coated article has a net compressive residual stress.
The features, aspects, advantages, and example embodiments described herein may be combined to realize yet further embodiments.